What you are doing works fine for the date submitted, but I also need the Submitter and there is no way to use max to get that value. Here is what I came up with throught trial and error and looking at some other posts. It seems to work:

I tried using a single join with a top 1 select query, but that doesn't work because the query is being used as a join condition, and I end up matching that top 1 record for all records in the Forum Table. I think this works correctly.